It has long been a primary objective of those working in the filing cabinet and business office furniture art to provide means whereby a filing cabinet may not only be locked against unauthorized entry but also to provide an anti-tip mechanism which secures the doors and/or drawers of the cabinet against the sequential opening of more than one drawer at any one particular time. It has also been a further and long time objective of those versed in the art to find a means whereby the foregoing objective could be economical fashion. That these objectives have not been satisfactorily achieved is evidenced by the multitude of inventions proposed to this end, representative of which are those disclosed in the following U.S. Pat. Nos. 3,900,236 issued Aug. 19, 1975; 3,199,937 issued Aug. 10, 1965; 3,888,558 issued June 10, 1975; 3,404,929 issued Oct. 8, 1968; 3,883,200 issued May 13, 1975; 3,602,564 issued Aug. 31, 1971; and 3,297,376 issued Jan. 10, 1967.
Filing cabinets heretofore proposed, such as those patents listed above, have suffered from a variety of deficiencies and difficulties. While the prior art anti-tip mechanisms have been generally successful in preventing more than one drawer from being opened at a time when the drawers are opened only one at a time, most such anti-tip mechanisms have been ineffective in preventing more than one drawer from being opened simultaneously. Thus, U.S. Pat. Nos. 3,888,558; 3,883,200 and 3,404,929 are examples of cabinets which do not prevent the simultaneous opening of more than one drawer and U.S. Pat. No. 3,602,564 is exemplary of a cabinet which includes a door interlock which does not prevent more than one door from being opened simultaneously. This deficiency in the prior art designs may lead to the upsetting of the entire cabinet when the cabinet itself is tipped slightly so that the drawers tend to run open of their own weight at the same time: a not uncommon circumstance when the cabinet is being moved. The solution to this problem proposed by U.S. Pat. Nos. 3,900,236 and 3,199,937 involve significant complications of the design of the anti-tip mechanism, which complications lead to excessive costs and difficulties in assembly of the cabinets.
An additional problem which has been encountered when prior anti-tip devices have been incorporated in filing cabinets is that such mechanisms frequently add additional depth to the cabinet and/or do not permit the drawer of the cabinet to be opened to a degree that the contents of the drawer can be removed vertically from the opened drawer. This difficulty is magnified when the cabinet is of the lateral file type in which cabinet depth is of primary importance and in which vertical deposit and removal of the filing material is a requirement. In an attempt to address this requirement, U.S. Pat. No. 3,900,236 has proposed a device having a complicated camming keeper mechanism which is subject to failure in the event that debris or rust were to interfere with the motion of the cam wheel and is both expensive and difficult to fabricate. Furthermore, since the keeper mechanism is actuated upon opening and removal of one drawer from the cabinet, and is not deactivated until the drawer is returned to its closed position, all of the remaining drawers are prevented from complete removal from the cabinet in the event that it is desirable to lighten the cabinet to facilitate its transport by the complete removal of all of the drawers. Accordingly, the file cabinet disclosed by U.S. Pat. No. 3,900,236 can be lightened by the complete removal of only one drawer at any one time, which capability may not be of any significant help when the cabinet is transported. Further lightening of the cabinet requires the inconvenient expedient of removing the contents of the other drawers rather than complete removal of the drawers themselves.